Self-levelling ladder



J. W. BENDICK SELF-LEVELLING LADDER Original Filed Jan. 21, 1954 June16,1959

5 Sheets-Sheet 1 W Tm mm. V vmu w a, H M m 8 I b i m 4 m; Mm y V\nrrorqyevs.

June 16; 1959 I SELF-LEVELLiNG LADDER Original Filed" Jan. 21, 1954 J.w. BENDICK 5 Sheets-Sheet 2 INVSNTOK;

JACK w. BGN DICK Arrowevs June 16, 1959 J. w. BENDICK 2,890,823

I SELF-LEVELLING LADDER Original Filed Jan. 21, 1954 f s sheets-sheet 5mvem'rok JACK w. BeN mcK BY ATTOKNGYS.

United States Patent 19, 1957. This application June 1, 1954, Serial No.

' Claims. (Cl. 228-29) This invention relates to a four legged structuresuch as stepladders, platform ladders, stairwell ladders, trestles andthe like which are constructed so that the legs will automaticallyconform to an uneven surface within reasonable limits and thus be aself-levelling feature. The term ladder as used herein includes all ofthe foregoing devices.

This application is a continuation of my application Serial No. 405,424,filed January 21, 1954, now Patent No. 2,781,961, granted February 19,1957, for a selflevelling stepladder as therein defined. Thatapplication described a construction in which the back legs or props andthe front legs are connected together by means of a pin and slotconstruction to allow the front and back legs to cant or to shiftangularly with respect to the front legs, the pins assuming differentpositions in their respective slots according to the unevenness in thefloor on which the ladder is standing. Thus, by swinging one side of theback leg downwardly and toward the front of the ladder while the opositeside of the leg is moved upwardly and toward the back of the ladder, anoffset in the level of the leg extremities of as much as one inch can beobtained. The front and back legs are each constructed to form a rigidunit so that they move as a unit. Therefore, the ladder levels itself atleast as soon as any weight is placed upon the first step. In the saidapplication, it will be seen that the levelling is effected by what maybe termed a back and forth movement of the top end of the back legstructure relative to the front leg structure which has the effect ofraising or lifting one leg of the pair of back legs and lowering theother. There will be the same relative movement of the front legs. Inthe present invention, the self-levelling of the device is obtained by alateral movement of the back leg structure from side to side relative tothe front leg structure or vice versa. By the term lateral I mean amovement in which the back leg structure moves in a substantiallyhorizontal plane at right angles to the back and forth movements in mysaid prior application. I thus obtain a tilting action of the pair ofback legs which has the efiect of raising one of said pair of back legsand lowering the other of saidpair.

In the present application, I have illustrated several modifications ofmy invention as applied to a conventional stepladder but its adaptationto other structures will be obvious to those skilled in the art.

ladder is adapted to be rested when the legs are in open position. Thepins of said pin and slot interconnections are slidable within saidslots, thereby permitting one of said pairs of legs to tilt laterallywith respect to the other of said pairs of legs in accordance withirregularities in the surface of a floor upon which said ladder isrested with its legs in open position and supplemental means forlimiting the spreading apart of said pairs of legs with respect to oneanother.

For an understanding of the invention, reference is to be had to thefollowing description which describes several embodiments of the same asillustrated in the accompanying drawings in which:

Figure 1 is an elevation taken from the rear, of a stepladder embodyingone modification of the present invention;

Figure 2 is a fragmentary perspective View of the top portion of theladder shown in Figure 1;

Figure 3 is a cross sectional view on the line 3-3 Figure 1;

Figure 4 is a fragmentaryperspective view of the top end of a stepladderemploying an alternative construction to that shown in Figure 1;

Figure 5 is a fragmentary perspective view illustrating anotheralternative construction;

Figure 6 is a cross sectional view on the line 66 Figure 5; H

Figure 7 is a fragmentary perspective view showing the topend of astepladder embodying still another alternative construction of theself-levelling device;

Figure 8 is a rear view of the ladder constructed in accordance with themodification illustrated in Figure 7;

Figure 9 is a fragmentary view, on an enlarged scale, illustrating thepin and slot interconnection shown in Figures 7 and 8;

Figure 10 is a fragmentary rear view of the top end of the ladderillustrating a further modified form of the invention;

Figure 11 shows an alternative construction of a cross section taken onthe line 11-41 Figure 12 of an alternative construction of a legbracket;

Figure 12 is a side elevation of the leg bracket shown in Figure 11;

Figure 13 is a side view of the top end of a trestle with;

In one modification, the self-levelling ladder of the associating eachleg of one pair with the corresponding leg of the other pair, the slotsof said pin andslot interconnections being relatively elongated, andbeing angulated withrespect tothe plane ofa floor upon which said 14-14Figure 13;

Figure 15 is an alternative construction of the leg bracket;

Figure 16 is a fragmentary view, on an enlarged scale, of a horn to showthe notch construction.

Like characters of reference refer to like parts throughv out thespecification and drawings.

Referring first to the construction illustrated in Figures 1-3, theladder includes a pair of parallel front uprights or legs 100, 101 whichmay be made of wood or metal and rigidly interconnected one with theother to form a rigid front leg structure, a pair of rear legs 102, 103rigidly interconnected with one another to form a rigid back legstnucture, brackets 104, 105 suitably mounted on and secured to theupper ends of the front legs 100, 101 respectively, a platform 106 whichis supported by the brackets 104, 105. Each of the brackets 104, 105extend rearwardly from the front leg with i which it is associated andis then bent inwardly at right angles toform extensions 107, 108respectively which underlies the rear or back edge of the platform 106.

The means by which the back legs are pivotally asso- .ciated with thefront legs so as to have pivotal move Figure 14 is a fragmentary sideview of the top portion of the trestle shown in Figure 13 taken on theline pin interconnection for associating-the front .leg structureandtheback leg structure totilt'as' hereinbefore mentioned, consists ofangulated slots 111,112 formed. in the extensions 107, 108 .and.pins'fllf 114 ,attached to the crossmember .109 and slidinglyfitted'into the slots 111, 112 respectively. The slots are arranged atan angle of between 45 to'6 .to the vertical centreline of theladderwith the preferred angle being about 54. 7 In Figures 1"ancl2 theslots111,'112 are shown as being inclined upwardly and inwardly towardsthe centre line. However, the slots may incline downwardly. andinwardlyas illustrated in Figure 4. It will be .observed that in bothconstructions the slots converge towards each other arthe anglesmentioned relative to the vertical centre line.

The back legs are maintained in a spread position at the correct anglerelative to the front'legs'by a standard type of spreader.

.Figure 1 illustrates the ladder standing on an 'uneven surface with theresult that the frontleg 101 is ata higher elevation than the front leg1'00 and both the front legs are at a higher elevation than the rearlegs 1'02, 1'03 respectively. The pinand slot construction hereinbefore.

described allows the-back leg structure to tilt or rotate laterally onits horizontal axis in a clockwiseor counterclockwise directiondepending on the nature of unevenness of the floor. This movement of thepair "of back legs as a unit has the effect of causing the pm 113 to.

slide toward the toplimit of the slot 111 and the pm 114 to slide towardthe bottom limit of the slot 112 which has the efliect of raising theleg 102 and lowering'the'leg 103 respectively. When the ladder haslevelled itself, the

movement stops. This movement is accomplished by the simple expedient ofat least the application of the-weight of a person stepping on thebottom step of the-ladder;

In some cases the weight'of the ladder alone will besufficient to causethe self-levelling action'to take place.

Pivotally mounted between the rear legs 1 02, 103 is a bucket rack 115.'Placed between the side members of the rack and the'backlegsare wedgeshaped inserts 116, 117 which are fastened to the back of the legs 102,103, respectively, with the narrowportions pointing upwardly. The-bucketr-ack fits between these inserts which permit the front end of the sidemembers of the bucket rack,

which-are cut somewhat at-an angle, to'bear against the top step of theladder.

:Referring now to Figure 4, I' have therein illustrated a modifiedconstruction in which the pin'and 4 sions 107a, 10811 of the bracketsare formed with holes 118, 119 through which the pins 120, 121 areinserted. These pins are not movable in the slots. The cross member 109ais formed with angulated slots 111a, 112a, similar to the slots 111 and112 and disposed at an angle within the range of angles previouslydescribed.

Referring now to Figures 5 and, 6, I have therein illustrated anotherconstruction -of-my invention. In that construction, theladder comprisesa pair of front legs 10% and 10117 which are formed into a rigid frontleg structure and the pair of back legs -102b,103b formed into a rigidback leg structure. Securelyattachedtothe top 'end of the frontlegs10011 and 101b are a'pairof brackets 122 and 123 which are turnedinwardly at right angles thereto to form arms 124, 125 respectivelylying immediately below the back edge of the platform 1061). Thus thebrackets 122, 123 are substantially L-shaped and support the platform10Gb. The rearwardly extend- 'i constructionjust described withreference to Figures 5 3 ing portions of brackets 122, 123 are eachperforatedforthe purpose to be hereinafter explained, these perforationsrbeing identified bythe numerals 126,127 respectively. .In punching theholes 126, 127, the material is not completely removed butsufiicientmaterial is left to form a flange 138 to provide a bearing surface forthe. back leg brackets hereinafter described with reference to Figures'Sand '6. The top ends of the pair of rear legs 102b, 103b are rigidlysecured together by a cross member-128. The pin construction in thepresent modification for connecting the back leg structure to thebrackets 1'22 and 123 consist of a pair of back leg brackets 129, 130which are substantially U-shaped. The back. leg brackets 129, 130aresecurely attached, with the open .ends down, .to the cross member 128so as to associate each-leg of the back leg structure'with thecorresponding leg of the front leg structure. Each of the back .leg

brackets have an angulated portion which connect. the arms of eachbracket. The angulated portions of the ..brackets 129, 130 areidentified by the numerals 131,

132 respectively and disposed at an angle corresponding with the angleof the slots previously described. The

angulated portions 131, 132 are slidably fitted into the orifices 126,127 to slide longitudinally therein. The

and 6 permits the back leg structure to tilt exactly the same as theconstruction previously described in conjunction with Figures 1 to 4 andto be hereafter describedwith reference to Figures 8 to 16 inclusive. Inthis construction there will be someslippage down the angulated por- Iand 1010 and a pair ofback legs 102a and 1030, the legs. of each pairbeing interconnected to form a rigid front slot .interconnections'havetheir positionsreversed, that is the pins are carried by the bracketsand the'slots are formed 'i-nthe cross member which is pivotally mountedon the-top endof the pair of rear legs. In this modification, brackets104a, 105a, bent inwardly to form extensions 107a, 108a respectivelywhich are similar in con- 7 the cross. member 109a by pivot pins l l 0awhich are entered ;through holes 151 respectively formed in the topendof each leg and holes .152 for-med'in the inturned ends 15 3 of themember 109a. This means of pivotally connecting the back-legs to thecross member 109a is. the

me/as. that.s wa..in. .Fiaures 1.2 @913. tT e xt n us tion should theweight be concentrated on oneside of the ladder. Under ordinarycircumstances where the weight on the ladder is more or less centralthere 'will be no slippage.

Referring now to Figures 7 to 10 inclusive, the modifications thereinillustrated are basically similar tov the modification illustrated inFigures 5 and 6. i In this construction, the ladder comprises a pair offront legs a leg structure and a rigid back leg structure respectively.Mounted on the top end of the front legs 1000, 101c is a pair ofbrackets 133, 134 respectively which extend rearwardly relative to thefront leg structure. Supported by the brackets is a platform 1060'. Therearward end of each of the brackets 133, 134 has. a round or ovalstraight punched hole 136, 137 respectively .so that the sidesof thehole are practically at right angles, the holes being provided toreceive the ends .of the back leg brackets to be hereinafter described.The top ends of the legs 102e, 1030 forming the hack leg structure arerigidly connected together by means of a cross member 154. The

pin construction for connecting the' back legfstru'cture to the'brackets133,134 consists of a pair of back leg brack- 'ets 139, 140. These'legbrackets'may 'besh'aped 'dif ferently as-shown inFi-gures'7 toldinclusivelybuteach pair.of.leglaracketsiisprovidedwithangulatedhomslfl;

a 142 respectively, the horns 141, 142 lying at the same angle andconverging towards each other in the same manner as the slotshereinbefore described.

Each horn is formed with a series of notches 138 upon which the brackets133, 134 rest. The notches may be of various shape, but in the preferredconstruction, the notches have a substantially horizontal surface uponwhich the brackets rest. This is achieved by having the notches shapedlike a wide V. As will be seen by reference to Figure 16 the notches 138are arranged in a series to simulate steps of a stair with the portion138a representing the tread which lies substantially in a horizontalplane with the front and rear leg spread apart. The riser portion of thestep, indicated by the number 138b is inclined slightly away from thevertical so as to assist the bracket sliding up and down the horn duringthe self adjusting process. The notches act as steps and the bracket onone side is prevented from slipping off the notch by the bracket of theother side which must ride up the born before the first mentionedbracket slides off its notch. Once the ladder has been levelled and thebrackets rest on the steps of the notches, there will be no slippagedown the horn when weight is applied to one side of the ladder. In thelevelling process the brackets slide up and down the respective hornsuntil the proper notches have been reached, thus lengthening andshortening the respective legs so that the ladder will rest firmly onthe uneven surface. The back leg brackets are preferably constructedfrom high tensile steels thereby permitting smaller dimensioned bracketsto be used without detracting from their ability to withstand any andall pressures or forces that may be applied to them without bending inuse. One of each of said pairs of leg brackets is secured to or mountedon the end of one of the pair forming the back leg structure. The horns141, 142, ride in the perforations 136, 137 respectively whereby thelegs work from side to side in levelling the ladder as hereinbeforedescribed.

Figures l1, l2 and 15 illustrate an alternative construction of the legbracket shown in Figures 7 to 10 inclusive. In each of these views onlythe top end of the front leg 1010 which carries the bracket 134 andplatform 1060, the bracket being punched to form the hole 136therethrough for receiving the horn 141, and the top end of one of theback legs namely back leg 102c is shown. The leg bracket 139 is securedin place by bolts 155, 156. The horn 141 in the construction illustratedis also formed with notches 138 previously described to provide steps onwhich the bracket 134 is supported to prevent slippage down the slopinghorn when the weight on the ladder is shifted from side to side as isusually the case when a person is working from the ladder. When theselflevelling device is used on heavy duty ladders, it is recommendedthat the free end of each horn, as illustrated with reference to thehorn 141, be supported by a sup port plate 158 which is secured to theupper end of the leg 102c by the bolt 155, the upper end of the plate158 being perforated to receive the free end of the horn.

Referring now to Figure 15, the support plate 158 (Figure 11) is formedintegrally with the prong so that there is provided a leg bracket 139having an angulated horn 141a formed with notches 138, the horn having adownturned extension 159 which is secured to the upper end of the leg102c by bolt 155.

4 Referring now to the construction of the trestle shown in Figures 13and 14. The trestle therein illustrated comprises a front leg unitconsisting of upright legs 200, 201, connected together into a unitaryrigid front leg structure by spaced apart rungs 202 and a back legstructure consisting of the upright legs 203, 204 joined into a rigidback leg structure by spaced apart rungs 205. The top end of the frontand rear leg structures are joined together in the manner hereinafterdescribed. The legs are maintained in proper spread apart position by apair of spreaders 221, 222, the spreader 221 being connected to thefront and rear legs 200, 203, respectively, and the spreader 222 beingconnected to the front and rear legs 201, 204 respectively. Eachspreader is formed of two parts pivotally connected in the centre toallow the spreader to told when the ladder is closed.

The preferred construction for pivotally associating the front legstructure and the rear leg structure to permit the leg structures totilt relative to one another as Well as pivotally moving towards eachother from operl to closed position, is similar to that hereinbeforedescribed in connection with Figures 7 to 10 inclusive with suchmodifications as are necessary to adapt the same to the trestle andtrestle extension hereinafter described.

Mounted on the top end of each of the front legs 200, 201 are brackets206, 207 respectively. Each of the brackets are similar in constructionand are L-shaped so as to provide each bracket with a rearwardlyextending arm 208, 209 respectively. The arms 208, 209 allow the topends of the front back leg structure to be spaced apart sufficient toallow the extension ladder unit consisting of legs 210, 211 which areconnected together into a rigid extension ladder unit by rungs 212 to bemounted so as to be slidable vertically between the top ends of thefront and back leg structure. Each of the arms 208, 209 are bent to forma guide channel 223 for guiding and supporting the legs 210, 211 of theextension unit the channels being completed by plates 213, 214 mountedon the upper ends of the legs 203, 204 respectively which, when thefront and rear leg units are in spread apart or open position, bearagainst the legs 210, 211 respectively to increase the verticalstability of the extension unit. Pivotally mounted on each spreader 221,222 and positioned thereon to be in vertical alignment with the guidechannels 223 are U-shaped guide members 224, 225 respectively. The lowerend of the extension unit legs 210, 211 ride in the guide membersproviding vertical stability to the extension unit. This constructionalso allows the trestle unit to be folded for convenience intransporting.

The means for connecting the rear leg structure to the front legstructure will now be described. This consists of a pair of leg bracketsthe same as leg brackets 139, mounted on the top end of the legs 203,204 respectively. Due to the position of Figure 13, only the bracket 13%on the leg 203 is visible. Consequently only the leg bracket on top ofthe leg 203 will be described, it being understood that the descriptionwill apply, as well, to the leg bracket on top of the leg 204. The legbracket 139 which is mounted on the top of the leg 203 is described inrelation to Figure 9, and consists of an angulated horn 141 havingstepped notches 138, the horn being inserted through the hole formed inthe rear end of the arm 208. This construction permits the front legstructure and the rear leg structure to tilt relative to each other soas to take up unevenness in the floor level as well as allowing thefront and back leg structures to be pivoted towards and away from eachother to open and close position in the manner hereinbefore described.The structure for supporting the extension ladder structure in anadjusted vertical position consists of supports 219, 220 which arehingedly connected to the top end of the legs 200, 201 respectively. Thesupports 219, 220 have their upper ends concave to form a seat for therungs 212. The hinged supports 219, 220 move out of position whenraising or lowering the extension. To raise the extension, the pressureof the brackets 213, 214 is relieved by bringing the legs 203, 204slightly in towards the front leg structure. The extension part is thenraised to the desired height, after rungs 212 have passed the supports219, 220, these supports fall back into position under the rung. Thelegs are then spread thereby applying pressure against the extensionladder through the brackets or plates 213, 214. To lower the extensionpiece, the reverse procedure is adopted.

"What I claim -as new and desire to Patent ofIthe .United-.States is: 1.',A-self?levelling laddercomprising a pair of front legs permanentlyconnected together forming a rigid frontleg unit, a pair of back-legspermanently connected together to form a rigid back leg unit andcomplemented parts including pin and slot interconnections respectivelyassociating .each leg of one pair with the corresponding lcg-of'theother pair, the parts of said pinand slot inter- Connections being.slidable relative to each other, and one part heingangulated withrespectto the planeof a floor upon which said ladder is adapted to berested when the legs are .in open position andin a directionto permitone of said-leg units to have limited rotative movement in alateraldirection relativeto the other leg unit to automatically changetheelevation of one leg of one unit relative to the other legs of theladder whereby the four legsof the ladder automatically adjustthemselves to an uneven floor surface and automatically lock in theadjusted position when said ladder is under load with its legs .in openposition, and supplemental means for limiting the spreading apart ofsaid pairs of legs with respect to one another.

2. A self-levelling ladder according to claim 1 the additional featureof an extension ladder unit mounted perpendicularly between the frontand rear leg units, and meanscarried by the-said brackets and thespreaders for maintaining the extension in a perpendicular position, andhingedtmenibers mounted-on thetop-of each leg of the front leg unit,said members engaging with a rung of said extension ladder unit therebysuppo'rtingsaid unit at a predetermined height.

3. A'self-levelling trestle comprising a pair of front legsinterconnected to form a rigid front leg structure,

protect by Letters 3. pair ,of rear legs interconnected to form arigidrearlegstructure, a bracket havinga .rearwardly extending armmounted on the top-end of each front leg, each arm having perforationsat the rear end thereof a leg bracket mounted on .the top end of each.rearleg, each leg brackethavingan angulatedhorn slidably fittedintothe-perforation of the adjacentarm, two of said brackets Withrelated horns forminga pair, thehorns of the-pair being disposed atanangle ofbetween 45 and-65 to the vertical centre'line of the ladder whenin open position, the said horns converging towards each other, fa

series of step-like: notches. formed in the-upper surface of each ho'rn,and a spreader connecting the front and rear leg units -to,-prevent thelegs spreading beyond a predetennined limit.

4. A self-levelling trestle according-to claim 3 theadditional'featureof an extension ladder unit mounted perpendicularlybetween-the front andrear leg units, and means carried by the said brackets and the spreadersformaintainingtthe extension in a perpendicular position, andhingedmembers mounted on the "topofeaeh leg of the frontleg unit, said membersengaging with a rung or said extension ladder unit thereby supportingsaid unitat a predetermined height.

"5. 'A self-levelling ladder comprisingapair of front legs permanentlyconnected togetherlforming "a rigid frontleg unit, a pair of rear legspermanently connected together forming a rigid ba'ck 'l'eg structure,means .interconnecting the baCkand front leg structures at the upperends'thereof to permit the leg structure to have limited'rotative'nrovement in a lateral direction toautomaticallyultlaterai'lyrelative"to one another in addition to-thepivotal moveinent'of-the leg str-ucturestowards and away from eachother, said-means including a connecting-member associating each leg-ofone pair withthe corresponding leg oftheet-herpair-comprising-complemential parts,- -one-p'art being a slot andthe other part being apinslidably mountdin said slot, one *ofsaid partsbeing-anghldr-ly --disposed relative to the other part and beingangulated with respect to the-'planeof the floor upon which said ladderis adapted to rest when the legs are in-bpen position, said pin being,Islidabledn; said slot to have relative movement with respect .theretoin accordance with the irregularities in the esu-rfaeertof'ihe floorupon"which the ladder 'is 'standing with thejlegs in spread apartposition to automaticallychan'gevthe elevation 'ofone leg of oneunit-relative to -the:;0th er leg unit of the ladder whereby the fourtlegs sof-s the ladder automatically adjust -thernselves 1013.11 unevenfloor surface and automatically lock in theadjusted position when saidladder is under load and-aspreadencon: nectin g the front-andbacklegsto-prevent'the legs spreadingbeyonda pred'eterminedrlimit. t

v 6. A self-levelling ladder comprising a pair rof .-fro

legspermanently connectedvtogetherforming a-rigid front leg-unit, a pairof -rearlegs permanently-connectedsto gether to form a rigid backlegstructure, meansjintep connecting the back leg unit and front leguni-t at-the'upper ends thereof to permit the'leg structures toautomatically tilt laterally relative to one another in addition :toithe pivotal movement-ofthe leg structures towardsia-nd :away

from each other, said means including a connectinganem' berassociatnigeach legof oneunitw-ith the correspond- 'ing leg of the other unit, saidconnecting members 300111- prising complementalparts,-one;part being'a'bracketsand the other part being a pin slidably mounted ,inisaidbracket, said pinbeing angularly disposed relative do" the bracketand-being angulatedin a direction withnespect to thepla-ne of the" floorupon WhlChiSZi'ld ladder zisadeirted to'rest whenthe legs are inopen-position:..to permitithe legunitsto tilt laterally relative to oneanother wherehy the Hfour legs of 'the ladder automatically adjust:themselves ,to an uneven :floorand automatically locktin the adjustedpositionwhen said ladder is under: load,,iand';a' spreader, connectingthej'front and back legsto; prevent the legs spreading :beyond apredetermineddimit.

7. A self-levelling ladder, according to claim 6m the bracket isassociated with and extended rearwardly from the'l'egs constituting oneof the leg units, therearward'sex'tension of the bracket having anorificeiozteceive the .angtilarly tdisposed' pin associated with thecorrespondingleg' of the otherl'eg structure.

8. A-"self-levelling ladder comprising a pair 'of front legs, the legsin said pair being permanently connected together to term acriigidfrontlegunit, a pair of back'ilegs' permanently connected together toform a back' leg unit, and means including pin and slotinterconnect-ionsrespectively. associating each leg: of one unitwith'the con esponding leg of the other unit, the pins of said pin and 1slot interconnections being relativelyelongated, and beingangnlated'with respect to-the plane ofa floor upon which said ladder isadapted to be rested, when the legs arein openposition, the pins of saidpin and slot interconnec tions. being slidable within said slots therebypermitting -i'= one of said-leg units to tilt laterally'with respecttothe other of saidleg unit in accordance with irregularities in thesurface: of a-floor upon which saidladder is res-ted with its legs inopen position, wherebythe tour-'legsoflthe two units automaticallyadjust themselves-to thesaid 'irreg-ul'a rities andautomatically lock inthe adjusted position-during the time the said ladderis under -load',and supplemental means for limiting the spreading apart ofsaid-pair's-oflegs with respect to one another.

9. A self-levelling ladder according to claim 8 in which eachpin-h-as-a--series of step-like notches formed-in upper surface, said pinbeing disposed at-an-angle of between 45 and to-theverticaleentre-l'in'e-of th'e ladder'When-in open position-to cause onebraoket-toslideup the pin; with which it is associated-an'd the otherbracket to slide down its pin until each bracket-is sup ported outhenotches with the bottom end of each leg res-tinglfirinly uponthe floor.

'10. -A self leve'lling ladder according to claim 8*inwhich thesa-idhorns converge towards each other, th'upper' ends being closer toeach other'than the lower ends.

References Cited in the file of this patent 2,054,690 UNITED STATESPATENTS 5%?221 273,474 Dennis Mar. 6, 1883 355,095 Macnider Dec. 28,1886 5 403,602 Neill May 21, 1889 519,535 Koehler May 8, 1894 5,433522,444 Wright 1. July 3, 1894 126,132 1,087,286 Franklin Feb. 17, 1914230,601

10 Barrett Sept. 15, 1936 Botinger et a1. Sept. 6, 1938 Nowick Nov. 12,1940 FOREIGN PATENTS Australia Mar. 21, 1933 Switzerland June 1, 1928Great Britain Mar. 19, 1925

